Benzene interaction energy, BSSE

The calculated interaction energy for the supermolecule method includes basis set superposition error (BSSE) [18]. The BSSE is corrected by the counterpoise method [19]. The energies of both dimer and monomers are calculated using the dimer s basis set in the counterpoise correction. The correction of BSSE is essential for accurate evaluation of weak intermolecular interactions, as the BSSE correction significantly changes the size of the calculated interaction energy. The effects of BSSE on the calculated interaction energy of the benzene dimer are illustrated in Fig. 1. 

Fig.l Effects of basis set superposition error (BSSE) correction on the benzene dimer interaction energy... 

As mentioned above, the method of KM is the most widely used variational energy decomposition method and works well for hydrogen-bonded systems, but it is not completely foolproof. Some of the shortcomings of the KM scheme include its limitation to only the HF method the final INT obtained is not corrected for unphysical lowering of energy caused by the basis set superposition error (BSSE). Also, molecular complexes separated by short distances, for instance, the cation-jt complexes of benzene with Li+ and Mg +, exhibit numerical instabilities in POL and CT energies. Several alternative schemes have been proposed to avoid problans of the KM EDA, one among which is the RVS analysis developed by Stevens and Fink and has been successfully applied to molecular complexes with various kinds of interactions. 

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